Digging tooth with hard-metal core



DIGGING TOOTH WITH HARD METAL CORE Filed Jan. 21, 1929 3 7 4; H5 j 1 Him! mvmh/ g ging tooth having a hard v have been composedv of heat treated a to have the p I II the body and casting the bod I .providean improved v STATES! [PAT-E ruin: A. enemies, or cmoiieo, rumors, assren'o'a 'ro mmucmimaa nnsr: swam. country, or cnrcaeo nmen'rs,

" reams roorn w'rrnnun-man con flppllcatlon filed Ianuary 2i, 1929. Serial. in. 888,789. a

an improved digmetal core and to Broducin'g the improved digigging teeth','such as teeth Th is invention-relates to a method of commonly formed from casting although in some cases a man anese steel ip er teeth loy steel or even carbon steel but none of these forms .10 have been entirely satisfactory since the edge would not wear-away uniformly tomaintam a relatively sharp digging edge. It is desired int of the dipper tooth com- I 'osed of harder metal than the remaining 1 Ody of the toothxso that the point which re-" ceives thegreater amount-of wear will be worn away at the same rate as the sides of the tooth, that is, the sides will be wornaway I more rapidly than the harder central point Z O b'ut the contour of the tooth will tained and a sharp cutting edge is be main presented for ;digging purposes at all times. It has been attempted to use inserts. of harder ma- 2 been-cast or forged by physical contact with the surrounding metal. 'In such a construction the insert, j which is not homogeneouslyjoined to the 1 body, is liable to break away and other difiiculties occur which render such constructions I impractical.

It is the purpose of. my invention to -pro-' vide in a dipper tooth or in anyar'tic'le re-.

I quiring a relatively sharp digging edge, an insert or a'pluralityof inserts composed'of of, relatively soft f material which is more joined to the body'by fusion between the surbetween the insert and the body.

It is further a purpose of my invention to digging tooth having a plurality of inserts of harder material than the body so arranged and spaced that upon .wear of thetooth in use the softer body will tooth h "the body and in which a body of manganese steel, is cast around an terialthan the body but these inserts have I and held in place only -3 '3F of Pi relatively hard and brittle material in a body, tough and ductile and in which the insert is,

faces of contact. This may be done'by pro be worn away between the inserts and present a serrated digging. ed e. f I

A further object o my invention resides in an improved method of forming a dipper aving. inserts which are harder than steel, or other allog insert which. upon eat treatment of the completed article, such as by quenchin will harden the insert to adegree that is harder than the outside body of manganese steel or other alloy steel. y v A further object of my invention resides n an improved method of constructing'an improved diggingtooth in which the'inserts of relatively-hard material are supported in a mold so that thebody of relatively softer material may be poured around theinserts and in which the material composin the body has a higher melting 'point an will unite with the inserts by fusion. I

Further objects'and advantages will be more readily apparent as the description proceeds in connection with the attached drawings, 'in which- I I v I 7 7| Figure 1 is a side elevation of my improved dipper tooth showing the projecting su portmg (portion'of the inserts which is held infthe I mol during casting. p Figure 2 is a top plan view of the dipper tooth shown in Figure 1 withtheprojectmg portion of the inserts broken-ofi'. I

Figure 3 is a sectional elevation on line re 1. I Figure 4 1s a lan of the lower portion of a mold showing the manner of supporting the inserts-therein. I Figure'5 is a plan view of a-plurality of inserts secured to a supporting portion.

My invention is disclosed in. the drawin in connection with a dipper tooth which is' adapted to be secured to the lip or sub-base of an'excavating bucket but it will be clearl apparent that a similar construction and method couldbe followed in connection with 1 other articles having a relatively sharp digging edge.

In the drawings I show a dipper tooth 1 having an acute angle point 2. The tooth is designed with rearwardly extending shanks 100 "T ce I 1 rumors, a" ooiarommox 'or Y 3 and 4 having a space therebetween but joined by a transverse web 5 in such a manner that the tooth may be joined to an attaching base or directly to the lip of the bucket.

Di per teeth have been commonly compose of alloy steel, generally manganese steel, and it has been necessary touse a steel alloy that is relatively tough and ductile and which will be sufliciently hard so that it will not wear away too rapidly in use, however, even with the use of manganese steel, difficulties are presented in that the point will not maintain its acute angle but w1ll wear away more rapidly at the digging edge'and finally assume a blunt point which is not as efficient in digging. It is, therefore, desired to so form the tooth that its contour will be maintained for a substantially long period of time in use. I

It is my purpose to provide a hard centralv insert or core or a pluralit of such inserts or cores extending inward rom the digging edge,'thus, I show in Figure 2, which is a plan view of the complete tooth, a plurality of inserts 6.. In Figure 3 the inserts are shown in section extending inward substantially the entire length of the tooth body.

-When the wear reaches the end of the inserts the tooth is discarded.

Although I show aplurality of inserts: it is my intention to include within my invention a dipper tooth having onl one insert. The inserts may be of any suitable cross section such as round, square, vrectangular or oblate. The inserts must be of material that is harder than the surrounding body, thus, the outer body may be of low' carbon steel which is tough and ductile while the central inserts are composed of hi h carbon steel 1 ance to abrasion but are relatively expensive.

which is harder and more brittle. Since the weight of metal comprising the inserts is relatively small as compared with the weight of metal in the dipper tooth, the inserts may be composed of some vof the newer alloyswhich have been found to have high resist- It will be noted that the digging edge of the "tooth which is composed alternately of the soft body and the hard inserts will wear away more slowly and the relative acute angle con- "tour of the tooth will be substantially 'main-' tamed. Furthermore, by the use of a plurality of spaced apartinserts, the wear on.

the tooth will cause the edge to be serrated, thus providing a digging edge which is more Inserts which have been commonly It is the purpose .of my invention" to homogeneously join the inserts to the body by fusmg the partsat their contacting surfaces.

One manner of bringing about the fusion between the inserts and the body consists in I cast into articles have been joined to the body only by physical contact and are liable to. become loose and fall out or break off in use.

providing a body which is of higher melting point-than the inserts and castin the body around the solid inserts whereby the surfaces of the inserts are somewhat dissolved by the molten metal and fusion occurs.

One method of casting the tooth will be described in connection with Figures 4 and 5. The member 7 is supported 'ina recess 8 formed in the bottom part of a mold 9 so that the inserts 6 centrally project into the mold and upon filling the mold with molten steel, the inserts will be surrounded by and fused into the cast body. The steel'may be sufiiciently over-heated so that it will remain molten in contact with the inserts for a sufficient period to start the dissolving or is tough and ductile and requires no heat treatment after the casting operation together with an insert of such material that it will be self-hardened and require no further heat treatment. On the other hand, I may use. such materials that the inserts will become hard and abrasion resisting and the outer body will become relatively soft, tough and ductile upon heat treatment after the casting is removed from the mold. In the first case I may use a low carbon steel for the body metal and a high carbon steel of lower melting point for the insert material which will not be softened by the casting operation. In the second case I may use manganese steel for the cast bodywhich ..will become tough and ductile upon quenching and an insert material which will become hard, brittle and abrasion resisting during" the quenching operation.v

Many modifications and changes may be made both in the selection of materials and in the method of forming the article without departing from the spirit of my invention as expressed in the appended claims. I claim:

1. An article of manufacture havinga dig" I ing edge comprising a body of tough, ductile, low carbon steel and a plurality of spaced apart inserts of hard, brittle, high carbon steel extending to the digging edge.

2. An article of manufacture havinga digging edge comprising a body of toug ductile, low carbon steel and a pluralit of spaced apart inserts of hard, brittle, high carbon steel extending to the digging edge, said body and inserts being united by fusion.

3. An 'article of manufacture having a digging edge comprising abody. of manganese steel and a plurality of spaced apart inserts extending to the diggin edge composed of alloy steel which is har er than the manga-- nese steel.

4. An article of manufacture having a digging edge comprising a body of manganese steel and a plurality of spaced apart inserts extending to the digging edge composed of alloy steel which is harder than the manganese steel, said body and inserts being united by fusion.

5. An article of manufacture having a digging edge comprising a cast metal body and a plurality of inserts extendin to the digging edge, said inserts being of arder material than the body whereby a serrated digging edge is presented as the edge is worn.

6. An article of manufacture having a digging edge comprising a cast metal bod and a plurality of inserts extendin to the iggin edge, said inserts being of harder materia than the body whereby a serrated digging edge is presented as the edge is worn, said inserts being united to the body by fusion.

7. A digging tooth comprising a body and a plurality of spaced apart inserts inwardly extending from the digging edge, said inserts Y being harder than said body whereby the wear on said tooth willform a serrated edge.

8. A digging tooth comprising a body and a plurality of spaced apart inserts inwardly extending from the digging edge, said-inserts being harder than said body whereby the Wear on said tooth will form a serrated edge, said body and inserts being united by fusion.

Signed at Chicago, Illinois, this 16th day of January, 1929.

FRANK A. FAHRENWALD. 

